潮汐瓦解事件的首个峰前紫外光谱：TDE2025aarm在最大光度前揭示的快速外流
First Pre-peak Ultraviolet Spectrum of a Tidal Disruption Event: A Fast Outflow Revealed Prior to Maximum Light in TDE2025aarm
- University of California, Berkeley（加州大学伯克利分校）
- Berkeley Center for Multi-messenger Research on Astrophysical Transients and Outreach (Multi-RAPTOR)（伯克利多信使天体物理瞬变与外展中心）
- Kavli Institute for Particle Astrophysics and Cosmology（卡弗里粒子天体物理学与宇宙学研究所）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
该研究首次在TDE2025aarm光学峰值前约20天获得紫外光谱，发现蓝移约10,000 km/s的宽吸收线，证实早期快速外流存在，并表明单温度黑体拟合会显著低估热光度。
AI中文摘要：
恒星被大质量黑洞潮汐瓦解并最终吸积的过程，可能引发外流和风，这些外流和风编码了关于潮汐瓦解和吸积过程的重要信息。然而，在光学光变曲线峰值之前，当流-流碰撞和吸积盘形成等过程可能很重要时，人们对外流的存在和行为知之甚少。在此，我们展示了潮汐瓦解事件（TDE）的首个峰前紫外（UV）光谱，该光谱在附近（红移$z=0.0137$）的TDE2025aarm光学最大光度前约20天获得，同时伴有准同步的红外（IR）至X射线观测。我们的HST/STIS光谱通过蓝移约10,000 km s$^{-1}$的宽近紫外（NUV）和远紫外（FUV）吸收线，为早期外流提供了强有力的证据，其中包括两个在TDE中尚未识别出的新紫外宽吸收特征。我们发现FUV-IR连续谱显著偏离黑体（$f_λ\propto λ^{-3.08}$），我们将其解释为通过外流再处理的标志。这种偏离意味着，当仅从NUV-光学光度学的单温度黑体拟合推断时，光学TDE中的热光度可能被显著低估（在这种情况下约为9倍）。这项工作进一步证实，TDE能够在极早期阶段发射快速外流，并强调了及时进行TDE的FUV光谱观测的重要性，这些观测可以捕获完整的连续谱发射和能量学。
英文摘要：
The tidal disruption and eventual accretion of a star by a massive black hole can lead to the launching of outflows and winds that encode important information about the tidal disruption and accretion processes. However, little is known about the existence and behavior of these outflows before optical light-curve peak, when processes such as stream-stream collisions and disk formation may be important. Here, we present the first pre-peak ultraviolet (UV) spectrum of a tidal disruption event (TDE), obtained $\sim 20$ days before optical maximum light of the nearby (redshift $z=0.0137$) TDE2025aarm, along with quasi-simultaneous infrared (IR) through X-ray observations. Our HST/STIS spectrum shows strong evidence for an early-time outflow through broad near-UV (NUV) and far-UV (FUV) absorption lines blueshifted by $\sim$10,000 km s$^{-1}$, including two new UV broad absorption features not yet identified in a TDE. We find that the FUV--IR continuum deviates significantly from a blackbody ($f_λ\propto λ^{-3.08}$), which we interpret as a signature of reprocessing through the outflow. This deviation implies that the bolometric luminosity in optical TDEs may be underestimated by a significant factor ($\sim$9 in this case) when inferred from single-temperature blackbody fits to NUV--optical photometry alone. This work further confirms that TDEs are capable of launching fast outflows at very early times and emphasizes the importance of prompt FUV spectroscopic observations of TDEs that can capture the full continuum emission and energetics.
